120 GELATINE, OR OSSEINE. 



The last portions, however, will contain hydrochloric 

 acid. 



5. Test the juice for lactic acid (see Lactic acid). 



6. Evaporate a quantity of the juice to dryness, and 

 burn. Examine the ash for phosphates and chlorides, 

 and for potash, soda, lime, magnesia, and iron. More 

 sodium will be found than potassium. 



7. Digest pieces of caseine or coagulated albumine in 

 gastric juice ; they will dissolve. Boil the solution ; it 

 will not coagulate. Add potassium ferrocyanide, lead 

 acetate, dilute alcohol, or a mineral acid ; no precipi- 

 tate will appear. Add solution of tannic acid or 

 mercuric chloride ; a precipitate will be formed. 



Gelatine, or Osseine. 1. Digest clean bones with 

 hydrochloric acid mixed with nine parts of water. 

 Replace the acid once or twice by fresh more dilute 

 acid, until nothing more is dissolved. Wash the 

 remaining mass repeatedly with water to remove acid, 

 and dry at a steam heat. 



2. Treat with cold water ; it will swell up but not 

 dissolve. Boil, and a solution will be formed. Use 

 the solution for the following experiments. 



3. Add a solution of tannic acid ; the gelatine will 

 be precipitated. No other acid will precipitate it. 



4. Add solutions of alum, ferric sulphate, potassium 

 ferrocyanide, cupric sulphate, or lead acetate. No 

 precipitate will be produced. 



5. Add mercuric chloride solution in excess. A 

 white precipitate will form. 



6. Boil one part of dry gelatine with four parts of 



